How do I push a value to a multidimensional array, before combining arrays?

[eluser]BernardoLima[/eluser]
I need to push a value to a multidimensional array, before format it to an array with key => value.
My approach was the following:

Code:

$keys = array('column1','column2','column3','column4','column5');

foreach($multArray as $c => $subarr)
{
  array_push($multArray [$c],'1'); /* This line was supposed to push a value, that would be the value of column 5 */
  $multArray [$c] = array_combine($keys, $subarr); /* Combines the values array with the keys array */
}


print_r($multArray );

But it's not pushing the value.
It's returning me the error:
array_combine(): Both parameters should have an equal number of elements

Does someone knows how to corrrectly do that?